In a web application I work on, I have been asked to change an existing 'Owner' field from being free-form to accept only predefined values from a list.
Sometimes that list can be manually configured by an administrator, and sometimes it can be retrieved from an LDAP search based on configuration.
I'm trying to figure out the best way to display this as an option, and a drop-down comes to mind as appropriate if the number of options is small (< 20), but if it's 50 or 100, or even 200, I'm not sure how to display that properly.
My question is: is it confusing to display different controls depending on the number of options?
That is, can I do something like this
- Fewer than 50 options --> show a drop down
- 50 options or more --> Show a text box with Ajax autocomplete
or would that be confusing to a user?
Am I going about this the wrong way? Should I just limit the number of options available and always display the drop down?